What Are Low-Carbon Concrete Options and How Are They Used?

Concrete is a staple product in the construction industry. However, its long-term use has proven just how much it's holding back the sector from minimizing its carbon footprint. You may have heard calls for companies to implement more sustainable practices, and incorporating low-carbon concrete is a step forward.

The importance of low carbon concrete

Low-carbon concrete is a category of materials that aims to have a lower carbon footprint compared to its traditional counterparts. It has the potential to reduce emissions by up to 50% in the long run. For reference, regular concrete is responsible for 8% of CO2 emissions worldwide, so halving that would have a significant impact.

Construction companies can also reduce waste, as most variations utilize recycled materials. Plus, certain variations of low-carbon concrete can provide you with the same level of durability and performance as regular concrete, if not better. 

Best Low-Carbon Concrete Options

Low-carbon concrete is a more general term for any engineered concrete material that minimizes its carbon footprint. Here’s an overview of the best options.

1. Supplementary Cementitious Materials

Supplementary cementitious materials (SCMs) are one of the most commonly known low-carbon concrete options. It has partially replaced Portland cement in 60% of modern concrete mixtures in the U.S., which is critical considering that it’s less energy-intensive.

SCMs can include many different aggregates, from fly ash to slag cement to silica fume and more. You can repurpose them to keep them out of landfills.

2. Geopolymer Concrete

Geopolymer concrete is another cost-effective option that minimizes environmental impact. The chemistry behind it was patented in 1979 due to the intricacy of the process. You should also know that it capitalizes on waste materials with silica and alumina.

Strides are being made to simplify the process, making geopolymer concrete more accessible, such as using suitable and high-quality raw materials. Improving the heat-curing application can also lead to better performance. 

  3. Limestone-Calcined Clay Cement

Limestone-calcined clay cement is a relatively new entrant into the low-carbon concrete market. It was invented in Switzerland and has the potential to account for over a quarter of the cement utilized globally by 2050.

The way this alternative minimizes emissions is by reducing traditional cement’s clinker content, which can be energy- and material-intensive. While only available in newly constructed cement plants, modifications can make it feasible for existing ones. 

  4. Alkali-Activated Concrete

Alkali-activated concrete is composed of select aggregates mixed with an alkaline solution, which is then triggered to harden and hold itself together, much like regular cement. You need to utilize the product in ambient temperatures for during and activating its self-compacting properties. 

  Getting the Most From Sustainable Concrete

Low-carbon concrete effectively minimizes environmental impact when used properly — therefore, you must be intentional about its integration. For example, using the correct water-to-cement ratio for the chosen aggregates is essential. Some types, like alkali-activated concrete, may require special additives.

It’s also vital to follow the preferred timelines and conditions for curing low-carbon concrete. Regular concrete needs at least seven days to withstand passenger car movement and other forms of pressure, and about four weeks to be fully cured. These time frames may vary significantly depending on the specific concrete option. 

Low-Carbon Concrete in Action

Low-carbon concrete has already been implemented in numerous projects worldwide. Recently, a more sustainable mixture was used for a new express lane on the Colorado State Highway. It utilizes coal ash, optimized aggregate gradations and recycled concrete aggregate.

Beyond infrastructure, low-carbon concrete suits residential, commercial and industrial buildings. It can even help your projects achieve greater sustainability and qualify for certifications like LEED.

Boost Sustainability in the Construction Sector

Low-carbon concrete is a promising solution for advancing sustainable construction. With continued innovation, it could reduce reliance on traditional concrete. Industrywide adoption and advocacy will help maximize its benefits, so make a difference with your material choice.